Answer: A (colored feathers.)
Explanation: There are many birds with colors that are variously different on the Galapagos.
So, Darwin carefully observed the finches of the Galapagos island. What he noticed was that they were similar to the mainland finches, but each island finch has different colored feathers.
When the bread and butter is in mouth, mechanical digestion starts. The size of the food gets reduced and it mixes with saliva for easy swallowing. The salivary amylase in saliva begins the digestion of starch in the bread. This is the start of chemical digestion. When the undigested bread and butter reached the stomach, lower esophageal sphincter relaxes and allow the chewed food to enter. The gastric secretions containing HCl, acts on the undigested food to produce chime. HCl kill the microorganism on the food and also denatures the protein and later attacked by digestive enzyme pepsin. Pepsin breakdown protein in the bread, butter . Later on gastric lipase begins to digest fat present in butter. Digestion of the starch in bread does not occur in the stomach because the salivary amylase that began chemical digestion in mouth became inactive in the presence of HCl. Further the chime enters the small intestine where bile secreted by the gall bladder emulsifies the fat and break into small globule which helps in fat absorption.
An Organ. Why does the answer need to be 20 characters long?
The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule. During this process, DNA polymerase “reads” the existing DNA strands to create two new strands that match the existing ones.
Every time a cell divides, DNA polymerase is required to help duplicate the cell’s DNA, so that a copy of the original DNA molecule can be passed to each of the daughter cells. In this way, genetic information is transmitted from generation to generation.
Before replication can take place, an enzyme called helicase unwinds the DNA molecule from its tightly woven form. This opens up or “unzips” the double stranded DNA to give two single strands of DNA that can be used as templates for replication.
DNA polymerase adds new free nucleotides to the 3’ end of the newly-forming strand, elongating it in a 5’ to 3’ direction. However, DNA polymerase cannot begin the formation of this new chain on its own and can only add nucleotides to a pre-existing 3'-OH group. A primer is therefore needed, at which nucleotides can be added. Primers are usually composed of RNA and DNA bases and the first two bases are always RNA. These primers are made by another enzyme called primase.
Although the function of DNA polymerase is highly accurate, a mistake is made for about one in every billion base pairs copied. The DNA is therefore “proofread” by DNA polymerase after it has been copied so that misplaced base pairs can be corrected. This preserves the integrity of the original DNA strand that is passed onto the daughter cells.

A surface representation of human DNA polymerase β (Pol β), a central enzyme in the base excision repair (BER) pathway. Image Credit: niehs.nih.gov
Structure of DNA polymerase
The structure of DNA polymerase is highly conserved, meaning their catalytic subunits vary very little from one species to another, irrespective of how their domains are structured. This highly conserved structure usually indicates that the cellular functions they perform are crucial and irreplaceable and therefore require rigid maintenance to ensure their evolutionary advantage.
Answer:
It's 3!
Explanation:
There must be genetic differences so the best fitted organisms will survive. If they were all the same then no one would be best fitted and Natural Selection wouldn't be able to occur
It's not 1 because a food shortage isn't required, there's always competition for food sources
It's not 2 because there doesn't need to be a change in the environment for natural selection, just for evolution.
And it can't be 4 if 1 and 2 are wrong!
Hope this helped!
